Can't use with --experimental-test-coverage --test

[gjuchault]

Acknowledgements

• I searched existing issues before opening this one to avoid duplicates
• I understand this is not a place for seek help, but to report a bug
• I understand that the bug must be proven first with a minimal reproduction
• I will be polite, respectful, and considerate of people's time and effort

Minimal reproduction URL

https://codesandbox.io/p/devbox/tsx-import-coverage-dkkgs3

I had to use codesandbox to have recent node version, you need local reproduction:

package.json

{
  "name": "nodejs-sandbox",
  "scripts": {
    "start": "npm run test-a || npm run test-b || npm run test-c || npm run test-d",
    "test-a": "tsx --experimental-test-coverage --test index.test.ts",
    "test-b": "NODE_OPTIONS='--import tsx' node --experimental-test-coverage --test index.test.ts",
    "test-c": "NODE_V8_COVERAGE=./coverage c8 -r html tsx --experimental-test-coverage --test index.test.ts",
    "test-d": "NODE_OPTIONS='--import tsx' NODE_V8_COVERAGE=./coverage c8 -r html node --experimental-test-coverage --test index.test.ts"
  },
  "devDependencies": {
    "c8": "^8.0.1",
    "tsx": "^4.6.2"
  }
}

index.test.ts

import { describe, it } from "node:test";
import * as assert from "node:assert/strict";

describe("case", () => {
  it("works", () => {
    assert.equal(1, 1);
  });
});

Version

4.6.2

Node.js version

v20+

Package manager

npm

Operating system

Linux

Problem & Expected behavior

I'm trying to get tsx to work with the native test runner, coverage included
It seems to be failing with the following warning:

ℹ Warning: Could not report code coverage. TypeError: Cannot read properties of undefined (reading 'line')

Also, c8 is not able to generate any report:

Unknown%

Contributions

• I plan to open a pull request for this issue
• I plan to make a financial contribution to this project

[privatenumber]

Is this a duplicate of #433?

[gjuchault]

Sorry for not spotting this issue earlier, I might have added a comment on it.
However, I tried with tsx@4.2.1 (pinned) as suggested by the author of #433 and I still get the same ℹ Warning: Could not report code coverage. TypeError: Cannot read properties of undefined (reading 'line') and no coverage, so I'm not sure it's exactly the same error

[gjuchault]

@privatenumber I tried the solution you suggested in #433 locally and ran npm link to try on my reproduction case. It still didn't run

Edit: also I've been running the code with Node v21.x where the condition is supposed to be true (process.setSourceMapsEnabled is defined and Error.prepareStackTrace is undefined)

[gjuchault]

Should be fixed by Node 22 since they merged this

[SuperchupuDev]

updating to node 22 doesn't solve the issue for me

[khaosdoctor]

Node team has addressed that in nodejs/node#52775 to remove the error, the coverage though is still useless.

One thing that we saw is that it probably has to do with the source map generation, but I haven't yet tested it

[privatenumber]

I left a comment in nodejs/node#52775 (comment), but tsx has source maps with V8 coverage support (released 5 days ago in v4.10.4).

I tested the minimal reproduction, and using c8 without --experimental-test-coverage works:

$ npx c8 -r html tsx --test index.test.ts
▶ case
  ✔ works (0.338ms)
▶ case (0.748625ms)
ℹ tests 1
ℹ suites 1
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 203.282667

Verified coverage is working with:

$ open coverage/index.html

But this doesn't with --experimental-test-coverage:

$ npx c8 -r html tsx --experimental-test-coverage --test index.test.ts
▶ case
  ✔ works (0.342167ms)
▶ case (0.768417ms)
ℹ Warning: Could not report code coverage. TypeError: Cannot read properties of undefined (reading 'line')
ℹ tests 1
ℹ suites 1
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 138.662125

IMO this is an issue blocked by Node.js

[SuperchupuDev]

works for me now using node 22.3.0, looks like it was a node issue fixed by nodejs/node#53315 which was just shipped

[privatenumber]

Thanks.

Confirmed working with Node v22.3.0:

➜  sandbox (1) npx c8 -r html tsx --experimental-test-coverage --test index.test.ts
▶ case
  ✔ works (0.363709ms)
▶ case (0.820125ms)
ℹ tests 1
ℹ suites 1
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 296.576208
ℹ start of coverage report
ℹ --------------------------------------------------------------
ℹ file          | line % | branch % | funcs % | uncovered lines
ℹ --------------------------------------------------------------
ℹ index.test.ts | 100.00 |   100.00 |  100.00 |
ℹ index.ts      |  33.33 |   100.00 |  100.00 | 2-3
ℹ --------------------------------------------------------------
ℹ all files     |  83.33 |   100.00 |  100.00 |
ℹ --------------------------------------------------------------
ℹ end of coverage report